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312
FXUS65 KBOI 212200
AFDBOI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BOISE ID
300 PM MST SUN DEC 21 2014

.SHORT TERM...STEADY PCPN CONTINUES TO COME IN FROM THE NW THIS
AFTERNOON AND SHOULD LAST WELL INTO THE NIGHT BEFORE DECREASING.
THE WARM FRONT DID NOT GO AS FAR NORTH AS EXPECTED AND TEMPS STAYED
RELATIVELY COOL. RAIN HAS CHANGED BACK TO SNOW AT MOUNTAIN SITES
ABOVE 6000 FEET MSL AND THE SNOW LEVEL SHOULD CONTINUE TO SLOWLY
LOWER THROUGH THE NIGHT AS PCPN CONTINUES.  ALSO...WINDS HAVE
DECREASED BELOW ADVISORY LEVELS IN SOUTHERN ZONES SO THE WIND
ADVISORY HAS BEEN CANCELLED.  THE WEISER RIVER ALMOST REACHED FLOOD
STAGE AT WEISER BUT APPEARS TO HAVE CRESTED THIS AFTERNOON.  OTHER
RIVERS WERE WELL WITHIN THEIR BANKS.  OTHERWISE...THE PREVIOUS
FORECASTS STILL LOOK GOOD EXPECTING PCPN TO DECREASE TO SCATTERED
RAIN AND SNOW SHOWERS MONDAY AND GENERALLY END LATE MONDAY.  TUESDAY
WILL BE A LITTLE COOLER THAN MONDAY IN THE VALLEYS BUT STILL
SLIGHTLY WARMER THAN NORMAL. MOUNTAINS SITES WILL START WARMING
AGAIN TUESDAY AS NEXT PACIFIC UPPER RIDGE COMES INLAND.

.LONG TERM...TUESDAY NIGHT THROUGH FRIDAY...A MORE WINTRY UPPER
LEVEL PATTERN ON THE WAY. AN UPPER LEVEL RIDGE OVER THE THE WEST
COAST TUESDAY WILL BE SUPPRESSED BY COLD UPPER LEVEL TROUGH IN THE
GULF OF ALASKA WEDNESDAY. AS THE RIDGE MOVES EAST A STRONG COLD
FRONT AND ASSOCIATED TROUGH WILL MOVE SOUTHEASTWARD FROM THE GULF OF
ALASKA INTO THE PACIFIC NORTHWEST. SNOW LEVELS WILL FALL TO VALLEY
FLOORS BY THURSDAY MORNING...ALTHOUGH IT IS STILL UNCLEAR WHETHER
SNOW WILL FALL BEHIND THE FRONT. STILL A GOOD CHANCE TO SEE
SNOWFLAKES FLY IN THE LOW VALLEYS FOR CHRISTMAS DAY...TRAVEL THROUGH
MOUNTAIN PASSES COULD BE TRICKY FOR WEDNESDAY NIGHT INTO THURSDAY.
GFS STILL DOES NOT HAVE A GOOD HANDLE ON THIS SYSTEM BECAUSE OF THE
INCONSISTENCY...THUS ELECTED TO USE THE ECMWF GUIDANCE. IN WAKE OF
THE COLD FRONT...EXPECT TEMPERATURES AROUND NORMAL AND PRECIPITATION
TO CONTINUE IN THE HIGHER TERRAIN MAINLY OVER THE BLUES...WALLOWAS
...AND CENTRAL IDAHO MOUNTAINS THROUGH FRIDAY. TEMPERATURE FORECAST
CONFIDENCE BEYOND THURSDAY IS LOW AS ANY NEW SNOW COVER WILL MAKE
TEMPERATURES COLDER.

FRIDAY NIGHT THROUGH SUNDAY...A COLD NORTHWESTERLY FLOW WILL AFFECT
THE REGION THROUGH SATURDAY...BECOMING WESTERLY BY SATURDAY NIGHT.
THERE IS A CHANCE OF PRECIPITATION IN THE WEST CENTRAL AND BOISE
MOUNTAINS BEGINNING SATURDAY NIGHT THROUGH SUNDAY. THE TURN IN WIND
DIRECTION SATURDAY NIGHT INDICATES AN APPROACHING SHORT WAVE
TROUGH WHICH WILL BRING A CHANCE OF PRECIPITATION TO MOST OF THE
REGION BY SUNDAY NIGHT. SNOW LEVELS WILL BE LOW...MOST PRECIPITATION
WILL COME IN THE FORM OF SNOW...AND TEMPERATURES WILL BE NEAR NORMAL
THROUGH THE PERIOD.

&&

.AVIATION...WIDESPREAD MVFR-IFR CONDITIONS WITH PRECIPITATION.
MOUNTAINS OBSCURED. SNOW LEVELS TO THE SURFACE IN CENTRAL IDAHO
MOUNTAINS RANGING UP TO 10K FEET MSL SW OF THE SNAKE RIVER
PLAIN...SLOWLY FALLING THROUGH THE NIGHT AS BAND OF PRECIPITATION
MOVES SOUTH. VFR CONDITIONS SOUTH AND WEST OF A LINE FROM KBNO-KREO
IN SE OREGON. SURFACE WINDS WESTERLY 15-25KT THIS EVENING IN SE
OREGON AND EASTERN MAGIC VALLEY EAST OF KJER...NORTHWESTERLY SURFACE
WINDS UP TO 15KT ELSEWHERE. NORTHWESTERLY WINDS 20-30KT MONDAY
AFTERNOON IN MAGIC VALLEY. WINDS ALOFT AROUND 10K FT MSL...NW 50-
75KT DIMINISHING TO NW 35-50KT BY 12Z MONDAY.

&&

.BOI WATCHES/WARNINGS/ADVISORIES...
ID...AVALANCHE WARNING IN THE SAWTOOTH RECREATION AREA UNTIL 730 AM
     MST MONDAY.
OR...NONE.

&&

$$

WEATHER.GOV/BOISE

SHORT TERM...LC
LONG TERM....KA/AB
AVIATION.....KA




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